Beyonce And I Fail Division

October 8, 2007

I avoid math as much as possible, but when there’s arithmetic to be done I have a calculator handy. Surprisingly, they still teach 6th grade math as if all calculators will spontaneously combust in 2015, which is why Finn is learning the tedious process of dividing complicated numbers by other complicated numbers.

There are infinite combinations of complications that I shudder to contemplate, for I’m sure they await Finn (and thus me) in the future. Dividing one fraction into another! Dividing a square root by an integer! Dividing percents! Dividing a negative number by another negative number, as if that ever happens in real life!

You notice I haven’t even reached the part where you start solving for X.

Finn needed help with his homework the other night, and Bill, the default, was out. I dispatched Finn to the shower so I would have plenty of time to work out the kinks in my teaching method.

The topic du jour was dividing decimals:

I knew exactly what to do as a first step; I rewrote the equation into proper division form:

I pondered this for a few minutes but the decimals were in my way, so I proceeded to the logical next step: a frantic call to the Voice of Reason. She majored in Economics and I’ve been calling her about issues raging from mathematical to culinary for more than twenty years.

“Have y’all already covered dividing a decimal number by another decimal number?” I asked.

“That’s what I was bitching about in Jazzercise last week,” The Voice said. “It’s a pain in the ass. Don’t tell me you’re helping Finn with math homework. Where’s Bill?”

It’s reassuring to have someone know you so well that she can instantly tell your husband is missing based on a phone call about homework.

“He’s in a deposition that’s running late. And I’m not completely incompetent in math, although this is really stretching my brain,” I said. “I remember something about flipping fractions over to divide them, so I was thinking dividing decimals would be a snap because there’s no gymnastics.”

“That’s true, you don’t have to flip anything,” The Voice said.

“Okay, so I have the big number in the hut and the smaller number outside the hut, but they both have decimals. Don’t I move them somewhere?”

“Yes, wait…” I listened as The Voice shuffled a piece of paper around and drew on it.

“You move the decimals over to the east as far as they will go, and then you solve the problem like you normally would,” she said.

“The east like the right?”

“Yes,”she said.

“Well, that stinks. Because if you moved them the other way, we could teach it by singing it like the Beyonce song: ‘To the left, to the left, pick up the dot and move it to the left,'” I sang.

“Yeah, that’s a big bummer,” The Voice agreed drily. “Now that you’ve moved the dot over, you just divide the numbers out the way you normally would, and then you put the dot– I mean the decimal– God, you’ve got me saying it too, back in place.”

So I moved the decimals to the east:

but I stuck a dot on the roof of the hut so I’d have some idea where the decimal would be returned at the end of the procedure.

I heard the shower shut off. Finn would be coming soon, so I had to be ready to teach.

I reviewed my notes and started working the problem out by hand. It was arduous, what with all the multiplying and carrying (which I still do on my fingers) and subtracting, so I got my calculator out and figured out that the answer would be
13.351408450704225352112676056338.

That was a hell of a number to contemplate sober. Solving it without technology would take all night and several sheets of paper even before I starting instructing Finn.

Worse, this answer didn’t exactly match the work I’d already done; I was sweating and I had come up with 1.335 so far. Clearly The Voice and I had a miscommunication as to where the decimal was going when it went back into the equation.

I poured a glass of wine and went back to the problem, this time ignoring the decimals entirely, and that’s how I ended up telling Finn to do it, too, for lack of a better option.

We came up with 133514 and then Finn and I had to figure out how to put the decimal in the right spot in the answer.

We ended up using the “sort of” method which they actually teach in third grade, only they call it “guesstimation.” Finn and I decided that 42.7 was sort of like 40, and 568.77 was sort of like 570, so the answer should be sort of like 13ish.

It worked for us, and I went to bed happy, since I knew we’d gotten the problem right.

Except we hadn’t. Finn came home the next afternoon and said we’d gotten points off for failing to follow directions. I looked down guiltily, wondering how my calculator use had been discovered. I’d been careful to put the calculator away before Finn ever came in the room.

It turned out that the instructions said to round to the nearest tenth, so our exuberant answer of 13.3514 looked downright suspect.

Ahh, well. Tis better to have divided well than never to have divided at all, I suppose.

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30 Comments

This post made that bit above my left eye twitch. I am not looking forward to this stuff. I was at parents’ night for my 7 year old a week or two ago and they told us that “they” have changed the way you do adding and subtracting! With numbers greater than 10, we were taught to add and subtract by doing the units first, then the tens then the hundreds – you know, so adding 43 to 28, you stacked them up, added 3 and 8, got 11, put the 1 in the units column, put another 1 in the tens column, added 4 plus 2 plus the extra 1 and got 7. Hey presto, 71! But apparently now they don’t! They do the bigger numbers first and then the units! Because that’s more “intuitive”. I feel betrayed…….

Okay, see if this makes sense.
1. You’ve got the “hut” right.
2. You don’t want a decimal number on the outside of the hut. So move the decimal east till it’s gone. COUNT THE NUMBER of spaces that you move the decimal. In this instance, you only have to move it one space.
3. Now, take the number inside the hut. Move its decimal the SAME number of spaces (making it 5687.7).
4. Now put the decimal on the top of the hut right over your new decimal’s location.
5. Now divide as normal.

Two semesters of calculus in college…don’t remember a lick. Algebra stuck, though….

Laura

The former 7th grade math teacher in me chuckled at the word hut. Never thought of it as a hut before, but it kinda works! And Carrie is right, the number on the outside of the hut determines how many times to move the decimal. Also once you move it, that is it’s new position-no moving it back. Essentially you are just multiplying both numbers by a factor of 10 to make the numbers workable. So long as you multiply both numbers by the same factor of 10 (10, 100, 1000, etc) you’re good to go. Feel free to pass any future questions my way.

My idea of hell would be a place that’s really hot where a creepy math teacher drones on and on for eternity, writing out long and complex equations on the chalkboard, and then assigns page after page of hideous problems like the one you just described. If it takes a whole dang sheet of paper to solve it, it ain’t worth figuring out!

Thank God my husband is proficient in the really difficult stuff. If what some of the comments say is true, I won’t be able to help my kids past first grade!

Jesse

I was going to say exactly what Carrie said, so I’ll just say she’s got it right. Instead of guesstimating where the decimal point goes, you just move it the number of spaces inside that you had to move it outside, and the answer’s decimal will be in the same (new) place as it is on the inside.

And just like Carrie, Calculus didn’t stick with me, but Algebra did. Although I’ll admit that to be sure, I put it out on paper. AND I kept my Calculus books, in case I wanted to re-try it on my own. Didn’t think of the possibility that my child might be learning it BEFORE college *sigh*. Well, she’s only 2 at the moment, so I’ve got some time to brush up, I guess! *grin*

Now, if only all my math teachers had been like my favorite one in High School, Mr. Jones, who let me do the problems however I wanted, so long as I showed my work! Would have saved me a lot of the uncertainty that I feel towards math today (though the problem REALLY isn’t me, it’s the backwards way that they make you solve some of those problems!)

Is there anything more guiltifying than helping your kid with his/her homework and getting a bad grade on it?? You can literally see their adoration and worship of you extinguish a bit each time it happens. I now make them sign disclaimers and Waivers of Responsibility when I help them. It’s much safer to my ego that way.

Eek! I hate – HATE – when my oldest needs help with his math. I’m all “here, this is how you do it.” Only to be told that that’s not how THEY do it. Greaaaat. And my degree is in mathematics … which is scary.

Also, thanks so much for your kind comment on my story. Your blog is one of my favorites, so I’m somewhat honored that you came by!

Karin

O.K., here we go again,moms back in school! I tried to help my son at one point only to be pointed out that my dinosaur ways were totally wrong. I really think it is up to these math teachers to get it in their heads by explaining it so that they understand it, and know how to work the problems. That’s THEIR job.

The math geek in me was very happy to read today’s post, and I see I’m not alone in that sentiment! I’d rather slog through long division than butcher French verbs and attempt to clarify the politically correct Sex Ed doublespeak when the time comes. Now there’s something Beyonce could sing about!

Great post! I would be okay helping my son with his math if it was the kind of math I actually learned myself. They don’t “put down the four anjd carry the one”, they “regroup the tens”. Huh? I end up explaining it all wrong! And like another commenter said, they don’t add from right to left, they add all the tens, then all the ones, etc. It makes no sense!

Long division actually makes sense to me, but when my kids take algebra? Where they have to solve for X and Y and whatever? I’m hiring a tutor.

Okay, I was with you on the hut, and I thought I remembered moving the decimals over to the right. But I didn’t realize you had to move them twice, just once I thought for the number on the left (to the left, to the left).

Bottom line is that I am sh!tting my pants and my oldest kid is only in second grade.

Cassie

Division doesn’t bother me, it’s geometry. I flunked it in high school. I begged the teacher to transfer me out, and he promised me he would make sure I’d pass. Lo and behold I flunked, I can handle anything, but geometry.

Jessica

There are a lot of math problems where I tell my son you have to be fair to both sides. You can’t leave the other guy out. Last year in 6th grade I was reviewing with him for a chapter test in decimals. When I told him how to move the decimal, he said “oh, that’s where they were getting it.” He didn’t want to ask the teacher and get a long lecture. Also, Parent of the Year I am didn’t believe he couldn’t see the board until April when I finally took him to the eye doctor. Be Fair to both sides. Equal. They do Algera too early now and have to have another math that I did not even take in high school to get an Advanced Academic.

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